a - A child of mass 30 kg travels in a lift. Calculate the force exerted on the child by
the floor of the lift when the lift moves (i) downward with an acceleration of 1.0 ms-2 , (ii) upward with an acceleration of 1.0 ms-2 What is the weight of the
child when the lift falls freely? Take g = 10 ms-2
b- A satellite of mass 200 kg is displaced by a distance of 2Refrom a point on the
Earth’s surface, where Re is the radius of the Earth. Calculate the work done on
the satellite by the force of gravitation. Take the values of the constants in your
calculation from the astrophysical data given in the course.
(a)
(i)
(ii)
(iii) In free fall the acceleration will be directed downward and we get:
(b) By the definition of the work done, we have:
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